Table 1.

Autophosphorylation of the two IR isoforms and IGF-I-R by insulin, IGF-II, or IGF-I

Cell line and receptorEC50 (nM) for receptor autophosphorylation
InsulinIGF-IIIGF-I
R cells
 IR-A0.8 ± 0.23.0 ± 0.4>30.0
 IR-B1.1 ± 0.424.0 ± 5.0>30.0
 IGF-I-R>30.02.5 ± 1.01.6 ± 0.3
CHO cells
 IR-A0.6 ± 0.13.8 ± 2.8>30.0
 IR-B0.7 ± 0.230.0 ± 6.6>30.0
 IGF-I-R>30.03.8 ± 0.42.1 ± 0.4
NIH 3T3 cells
 IR-A0.7 ± 0.23.6 ± 0.7>30.0
 IR-B0.8 ± 0.222.0 ± 4.0>30.0